编辑表格并保存到数据库

Question

I have a form that takes information about an item and saves it into the database. Im trying to allow users to edit that form with new/different information and save it again. Im having some difficulty trying to get this to work. I think the problem is when Django validates the data it sees that the slug and unique id of the item already exist and doesnt allow it to validate the data but im not completely sure about this as well. Would really appreciate the help. Thanks.

#view
def edit_item(request, item_id):
    if request.method == 'POST':
        item = Item.objects.get(id=item_id)
        form = AddItem(request.POST,instance=item)
        if form.is_valid():
            item = form.save(commit=False)
            item.user = request.user
            item.is_active = True
            item.slug = slugify(item.name)
            item.save()
            return HttpResponseRedirect('thanks.html')
        else:
            form = AddItem(instance=item )
            return render_to_response('forsale.html', locals(), context_instance=RequestContext(request))

#form
class AddItem(forms.ModelForm):
    name = forms.CharField(label="Title")

    class Meta:
        model = Item
        exclude = ('user','slug','is_active',)

#model
class Item(models.Model):
    user = models.ForeignKey(User)
    name = models.CharField(max_length=30)
    slug = models.SlugField(max_length=50, unique=True)
    is_active = models.BooleanField(default=True, blank=True)
    image1 =  models.ImageField(upload_to='img')
    image2 =  models.ImageField(upload_to='img', blank=True)
    image3 =  models.ImageField(upload_to='img', blank=True)
    image_caption1 = models.CharField(max_length=200, blank=True)
    image_caption2 = models.CharField(max_length=200, blank=True)
    image_caption3 = models.CharField(max_length=200, blank=True)
    price = models.DecimalField(max_digits=8, decimal_places=2)
    quantity = models.IntegerField(default=1)
    description = models.TextField()
    created = models.DateTimeField(auto_now_add=True)
    shipping_price = models.DecimalField(decimal_places=2, max_digits=6)
    categories = models.ManyToManyField(Category)

    def save(self, *args, **kwargs):
        super(Item, self).save(*args, **kwargs)
        if not self.slug:
            self.slug = slugify(self.product.title) + "-" + str(self.id)
            self.save()

Answer 1

Update your view function like this to return form for get request as well:

def edit_item(request, item_id):
    if request.method == 'POST':
        item = Item.objects.get(id=item_id)
        ....
        #your existing code
   else: #if its GET request
        item = Item.objects.get(id=item_id)
        form = AddItem(instance=item )
        return render_to_response('forsale.html', locals(), 
                   context_instance=RequestContext(request))

Note: you need to handle case when item with item_id does not exists in the DB. In that case do not use instance parameter to instantiate the form.